Melting and cracking – is Antarctica falling apart?
Antarctica boasts a great many superlatives: it is the driest continent, the coldest, the remotest, the windiest and the highest on average. Right now, during midwinter, it is also the darkest. As a rift on the continent’s Larsen C ice shelf lengthens and gets closer to the ice front, we are anticipating the detachment of a large tabular iceberg within the next few weeks.
This comes after observations of a waterfall on another ice shelf last summer, reports of extensive surface melting on several ice shelves and, in a report last week, indications of a widespread surface-melting event, which included rainfall as far as 82° south, during the 2015-16 El Niño. Are glaciologists shocked by any of this? Is Antarctica going to melt away? Is Larsen C about to collapse?
The answer to these questions is no. Glaciologists are not alarmed about most of these processes; they are examples of Antarctica simply doing what we know Antarctica has done for thousands of years. But because there is a potential link between the ice sheet and climate change, glaciologists are suddenly faced with a situation where the spotlight is on our science on a seemingly daily basis, and every time a crack grows, or a meltstream forms, it becomes news. The situation is a conundrum: we want people to be aware of Antarctica and concerned about what might happen there in the near future as climate changes. But hyping research results to sound like climate change, when they are just improved understanding of natural behaviour, is misleading.
There is plenty going on that merits concern: Antarctic ice shelves overall are seeing accelerated thinning, and the ice sheet is losing mass in key sectors of Antarctica. Continuing losses might soon lead to an irreversible decline. However, we do not need to press the panic button for Larsen C. Large calving events such as this are normal processes of a healthy ice sheet, ones that have occurred for decades, centuries, millennia – on cycles that are much longer than a human or satellite lifetime.
So, while ice fracturing and surface melting may sound like signs of climate change in action in Antarctica, they are really part of the background against which we must look for real change. Real changes are happening there, and when we report them they need to stand out. Previous collapse events involved large amounts of surface melt that forms ponds on an ice shelf that had already weakened. We have not observed this on Larsen C. We will continue to monitor Antarctica by satellites and from the ground, but we will not cry wolf about an imminent collapse of Larsen C.